The invention generally relates to an escalator and, in particular to an escalator with a traveling step conveyor guided between two bases for handrails and having steps with lateral safety devices.
In order to protect against the known latent danger of drawing-in or catching of light articles of clothing and light footwear between the traveling steps and the solidly attached lateral bases on escalators, various safety devices attached laterally on the steps have become known. The choice of such safety devices goes from simple color marking of the danger zone to complicated barriers laterally insertable on the steps.
A safety device for escalators includes, on both sides of each individual step, a protruding insert of synthetic material received in the furtherst sideward groove on the upper surface of the step as shown in the U.S. Pat. No. 4,397,383. The insert is produced by the extrusion process and has two flanges. For mounting on the surface of the step, the first flange is pressed into the outermost groove of the step. The second flange, protruding opposite the contact surface of the step, is supported towards the stepping side and is tiltable against the fixed base. In the unloaded condition, the protruding flange turns towards the base, without touching the same, and forms a clearance between the flange and the base, which is approximately equal to the clearance between the outermost solidly attached rib of the step and the base. If the flange is stepped upon by the shoe of a passenger, it bends towards the base, whereby the clearance between the base and the safety insert is closed. The protruding flange of the safety insert, which has the lowest possible coefficient of friction, glides on the base and prevents articles of clothing or light footwear of the passenger from being clamped between the step tread plate and the base and being pulled inward. An article, which in spite of this is eventually pulled between the synthetic material insert and the base, can be freed again with relative ease from the restraint due to the elasticity of the insert. An immediate application of a counterforce, if the restrained article has not been caught already by the solid edge of the step thread plate is required.
A drawback of this embodiment is that the open gap between the outermost tread plate rib and the safety insert, in particular the undercut between the protruding flange and the clamped flange of the safety insert, can become clogged with dirt in the course of time. Thereby the efficiency of the protruding flange is at least seriously restricted. This drawback has its effect increased in outdoor or open air installations or in installations in underpasses, where the dirt sediment can be extremely heavy, depending on the weather and the time of year. A further drawback lies also in the fact that the mounting of the synthetic material insert in the groove of a cast tread step with conically downward tapered cross-section and also due to the desirable low coefficient of friction of the material of the insert, allows the insert to easily be torn out of the groove. In spite of this safety device on the step tread plate, there exists a further latent possibility of catching and pulling-in of light footwear between the step risers and the base, above all in the upper and in the lower region of the escalator, at points where during the formation of the stair landings or the horizontal runs of the steps, relative movements become necessary between two adjacent step bodies.
A further protective device for escalator steps is disclosed in U.S. Pat. No. 4,570,781 in which protective inserts are arranged on the side edges of the tread plate and on the risers. The protective insert is made of elastic synthetic material by the extrusion process and, in one embodiment, is bolted onto the recessed edge section of the tread plate of the riser from the visible side, or in another embodiment clamped onto the outermost rib of a typical step. The protective insert of the first type has three ribs, where the outermost rib extends above all the other rib surfaces lying on a common plane. The tread of the outermost rib is set at an angle with respect to the other ribs and the bottom of this rib exhibits along the whole length a wedge shaped notch directed towards the base through which the entire rib can be moved with relatively light pressure towards the base or away from the base. The surfaces of the notch lying on top of each other serve as an end stop for the movement of the rib, simultaneously with the contact of the upper edge of the rib on the base. Serving as stop for the movement of the outermost rib, away from the base, is the upper edge of the second rib.
A drawback of this protective device lies in the fact that the notch, which is open towards the base, can likewise get clogged with dirt and thereby the possibility of movement toward the base is impaired or totally prevented. In the extreme case, the outermost rib could even be distant from the base, so that the space between the rib and the base sheet could increase in a wedge-shape and the danger of pulling-in would become greater rather than smaller. The protective device will only respond when the outermost rib is stepped upon or is loaded.